<html><head><title>foo</head>
<body>
<a>Here is an <unknown>unknown element</unknown> in some inline text</a>
<div>and <unknown>here</unknown> in some block text</div>
<p>and <unknown>here</unknown> in a paragraph</p>

<unknown>
<p>containing p tag</p>
</unknown>
<unknown>
<a>a tag</a>
</unknown>
<unknown>
<div>and a div</div>
</unknown>
</body></html>